From Pathfinder #170: Spoken on the Song Wind, which isn't enabled.

Spellender

ITEM 9

UNCOMMON AGILE FINESSE MAGICAL THROWN-10 VERSATILE-S

Price 600 gp

Usage held in 1 hand

Bulk L

Category simple

Group knife

Damage 1d4 piercing

This knife is a +1 striking returning dagger with a wide blade and thick wooden handle. A prayer for protection from evil magic is carved into the handle in tiny script, running around the handle in a spiral. The grooves of the carved prayer provide a good grip on the knife and make it easy to catch when it returns to your hand.

Activate envision

Frequency once per day

Trigger You critically hit with the weapon

Effect The dagger casts a 4th-rank Dispel Magic targeting the most powerful spell effect affecting the creature you critically hit. The counteract check is +15.

Pathfinder #170: Spoken on the Song WindOGL